David Cameron will apologise to the Queen after he was overheard saying she "purred" on hearing the result of the Scottish independence referendum.
A camera crew recorded the PM telling former New York Mayor Michael Bloomberg he had "never heard someone so happy" as the Queen after Scotland voted "no".
Mr Cameron has said he is "embarrassed" and "extremely sorry" for the remarks, the BBC reports.
He has contacted Buckingham Palace and will apologise in person when he next meets the Queen, Downing Street said.
Last Thursday, Scottish voters rejected independence from Britain by 55 percent to 45 percent.
Speaking in New York, Mr Cameron told Mr Bloomberg he had phoned the Queen to tell her the result.
"She purred down the line," he said. "I've never heard someone so happy."
He added: "It should never have been that close."